1. Technical Field
The present invention relates to an ultrasonic device, an ultrasonic probe including an ultrasonic device, and an electronic apparatus including an ultrasonic probe, and an ultrasonic imaging apparatus including an ultrasonic probe.
2. Related Art
A known ultrasonic device is configured to include a piezoelectric member, a backing unit, an acoustic matching layer, an acoustic lens, and the like. Ultrasonic waves generated by the piezoelectric member of the ultrasonic device are incident on a subject through the acoustic matching layer and the acoustic lens. Then, the ultrasonic device receives reflected waves (ultrasonic waves) that are reflected from the inside of the subject, and generates a voltage corresponding to the strength of the reflected waves. In addition, the backing unit supports the piezoelectric member and attenuates unwanted ultrasonic waves, thereby suppressing noise riding on the ultrasonic wave incident on the subject.
In a case where the piezoelectric member (ultrasonic element) is formed in a thin-film structure in which a piezoelectric layer is arranged in the shape of an array on a vibrating film on a silicon substrate, a metal plate is used as a backing member that forms the backing unit in order to secure the structural strength including the rigid force of suppressing deflection of the ultrasonic element array. In addition, since the backing member uses a characteristic that the attenuation of ultrasonic waves increases as the travel distance increases (thickness increases), a metal plate having a thickness equal to or greater than the rigid force is used.
JP-A-2007-134767 discloses an ultrasonic probe configured to include piezoelectric transducers arranged on a backing material. In the ultrasonic probe disclosed in JP-A-2007-134767, a backing material is formed of a composite material containing a fiber material and a resin, and the longitudinal direction of the fiber material matches a vibration direction of each piezoelectric transducer. JP-A-2007-134767 discloses that lightness and broadband frequency characteristics are realized to obtain a high-quality image by using such an ultrasonic probe. In addition, in the ultrasonic probe disclosed in JP-A-2007-134767, the piezoelectric transducer is of a so-called bulk type. Accordingly, as a backing material, for example, by dispersing tungsten powder slightly in a composite material containing an epoxy resin and carbon fiber, lightness is realized.
Currently, in order to improve the convenience of the ultrasonic probe or the ultrasonic imaging apparatus, it has been requested to make an ultrasonic device thin using a thin-film ultrasonic element (ultrasonic element array). Specifically, it has been requested to make a backing unit thin. In the case of simply reducing the thickness of the backing member in the related art, it is a problem that unwanted ultrasonic waves, which have not been attenuated by the backing member, are emitted to the ultrasonic element side to become a large noise component. In addition, since the noise component is displayed as artifacts in the Y-axis direction (depth direction) during B-mode imaging, the noise component is the cause of false findings in an examination or the like.
Therefore, an ultrasonic device including a backing unit that can suppress unwanted ultrasonic waves and can be made thin, an ultrasonic probe including the ultrasonic device, an electronic apparatus including the ultrasonic probe, and an ultrasonic imaging apparatus including the ultrasonic probe have been demanded.